VBM Junior HX - wire with sensor? attached to ULKA pump

Equipment doesn't work? Troubleshooting? If you're handy, members can help.

#1: Post by MuHyC »

Hi all,

I have a wire broken of sensor? which connect to ULKA pump in my VBM Junior HX.
Not sure how this blueish thing is called but it was attached to ULKA pump body. Here is whats written on it: F20N 580 033H.
Please see attached pic.
Can somebody please tell me how this sensor? called and if I can simply solder it back?
Thanks a lot!

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#2: Post by civ »

MuHyC wrote: I have a wire broken of sensor ...
It's an NTC sensor for protection of the Ulka pump in case it gets too hot.

Like these ones:
http://www.soundservice.gr/e-shop/en/pr ... ts_id=4457
http://www.ebay.co.uk/itm/DeLonghi-Sens ... 2283684234

Not too expensive, depending on where you purchase it from.
I seriously doubt you can fix it by soldering the wire, the heat will probably render it useless.



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#3: Post by Nunas »

It's a thermistor. The resistance varies depending on temperature. Yours is, as noted by others, a negative going (NTC) thermistor. They can be used as a temperature sensor (e.g., in an electronic thermostat), limit in-rush current, and to protect devices. Because yours is a negative going thermistor, the latter is what it's probably used for. As the pump heats, resistance of the thermistor increases, lowering the current through the pump. ULKA pumps are 50/50 duty cycle devices with a maximum one-time run of one minute (after which time you should let them rest for one minute to let them cool down). The fact that your machine has a thermistor tells me that your machine is of above average design. As ULKA pumps are cheap and don't run for long at any one time in an espresso machine, they are not usually protected.

MuHyC (original poster)

#4: Post by MuHyC (original poster) »

Thanks everyone for your input!
Any idea if I can simply remove it and just connect the wires without it?
I have troubles locating this particular one F20N 580 033H in Toronto, Canada or online in USA.

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#5: Post by Nunas »

Yes, I think so. ULKA pumps are made to run directly on mains voltage (120 or 240 depending on the model). When I replaced mine (same pump as yours) I tested it by connecting it directly to the mains with a cheater cord. You just won't have any protection for the pump.

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#6: Post by Nunas »

PS if you want to put it back with the sensor, you might try contacting US Sensor, Digi-Key or Mouser. If they can't supply an equivalent nobody can.


#7: Post by onthego »

MuHyC wrote:Thanks everyone for your input!
Any idea if I can simply remove it and just connect the wires without it?
I have troubles locating this particular one F20N 580 033H in Toronto, Canada or online in USA.
Yes you can run the pump without it. Chris Coffee Service in Albany, NY has them.

https://www.chriscoffee.com/Klixon-Ther ... klixon.htm


MuHyC (original poster)

#8: Post by MuHyC (original poster) »

Thank you all!
I bypassed the pump sensor and the pump seems to work but I have another small problem though .

Once I removed the pump sensor the machine is now always in "hot" state when plugged in regardless whether the machine ON/OFF switch is turned on/off.
I mean once I plug it in( even when the on/off switch is off) the machine responds to lower water sensor. i.e. when there is no water in the tank, the orange light indicating "tank lower water" lights up. Once I put water in the tank , the lower water light turns off and machine is in "kind" of "off" state. That is, its not heating up and not responding when engaging pull lever.
Once I turn machine ON (on/off switch ON) everything works as before. Water sensor, engaging pull lever etc.

Sorry for long and perhaps unclear explanation but it seems that machine gets power always now. Not sure if I screwed up something during removal of the sensor like burning some fuse? Is there any fuse or smth similar that I can check?

It sill works and I can pull the shots but this "ON/OFF" behavior is different from it used to be.

As I mentioned it's VBM (Vibiemme) Junior HX machine. It doesnt have any fancy electronics and it only has manual pull lever and just one switch (ON/OFF) which suppose to turn machine on/off.

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#9: Post by erics »

The VBM Domobar SUPER is wired such that the low water level switch always has power when the machine is plugged in. I can only ASSUME that the Junior is wired in a similar manner.

There is a very good electrical schematic of the Domobar Super on my crude FTP site (below my sig.). As far as I am concerned, your machine is operating properly.

Eric S.
E-mail: erics at rcn dot com

MuHyC (original poster)

#10: Post by MuHyC (original poster) »

Thank you, Eric, for the provided explanation and the diagram!
I guess I just never paid attention to this behavior before and I thought it was unusual when I first experienced it now.